This invention relates to franking machines and in particular to the provision of security in respect of use of such machines for franking mail items.
Franking machines are known for printing a franking impression on mail items, the franking impression including a value of postage charge and other postage data such as the date of printing the franking impression to indicate to a postal authority for postage charge has been levied on the mail item. Use of the franking machine is licensed by the postal authority and for reasons of security in handling of mail items franked with postage charge by a franking machine, the franking machine is permitted to be used at a single location and the franked mail items are handled by a specific postal office usually in the same general area at which the franking machine is located. The printed franking impression includes the name of the town appropriate to franking of mail items by that franking machine. In franking machines in which the invariable part of the franking impression, that is the parts of the franking impression other than the value of postage charge and the date which are variable, are printed by means of a printing die the name of postal town is included in the printing die. In franking machines which utilise digital printers in which a plurality of printing elements are operated selectively to print dots such as to build up line by line the franking impression, the franking machine stores print data to cause the printer to print the name of the postal town in the franking impression.